Acoustical sound producer for clocks, especially for wristwatches

ABSTRACT

A sound producer for a watch with a pin of ferromagnetic material attached to the watch crystal and directly excited by an electromagnetic system.

United States Patent [191 Sodler ACOUSTICAL SOUND PRODUCER FOR CLOCKS, ESPECIALLY FOR WRISTWATCHES [75] Inventor: Walter E. Sodler, Buchenbronn,

Germany [73] Assignee: Timex Corporation, Waterbury,

Conn.

22 Filed: June 17, 1974 21 Appl.No.:479,943

[30] Foreign Application Priority Data July 5, 1973 Germany 2334236 [52] HS. Cl. 58/57.5, 340/388 Mar. 11, 1975 [51] Int. CL... G04b 23/12, GO4c 21/34, GlOk 9/00 [58] Field of Search 58/38, 57.5; 340/388 [56] References Cited UNITED STATES PATENTS 3,462,943 8/1969 Spadini ct a]. 58/575 3,733,804 5/1973 Diersbock 58/575 X Primary Examiner-George H. Miller, Jr.

[57] ABSTRACT A sound producer for a watch with a pin of ferromagnetic material attached to the watch crystal and directly excited by an electromagnetic system.

.3 Claims, 3 Drawing Figures PATENTEDHW 1 m on Q om 2 liiii:

BACKGROUND OF THE INVENTION The present invention relates to an acoustical sound producer for clocks, especially for Wristwatches, with a pin attached to the watch crystal, said pin being able to be oscillated by means of an electromagnetic system excited by an oscillator.

A wristwatch with an electrically driven sound producer of this general type in which a plastic pin is formed to the plastic crystal is already known in US. Pat. No. 3,462,943 issued Aug. 26, I969. The electromagnetic system, which is excited by a common, selfstarting oscillator circuit, has an electromagnet arranged on a support between two permanent magnets as well as a tongue which is firmly clamped on one side and capable of oscillating, which projects beyond the poles of the permanent magnets and the electro magnet, and extends roughly at right angles to the pin formed on the watch crystal. If the oscillator excites the electromagnetic system, the oscillating tongue strikes the pin, thus exciting the watch crystal which serves as a resonator.

This known design has various disadvantages: To

provide sufficient volume of the acoustical signal, it is not only necessary to adjust the tongue of the electromagnetic system relative to the magnets, but the tongue, and thus the entire electromagnetic system, must also be adjusted relative to the pin. In addition, the watch crystal must naturally be excited with its natural frequency. Since, as a result of striking the pin, the tongue does not oscillate sinusoidally, the watch crystal is excited with a frequency spectrum, whose composition depends to an extremely great degree on the amplitude of the tongue. Adjustment of the electromagnetic system relative to the pin, temperatures and the charge of a battery thus significantly influence the exciting frcquencies, so that there is a great danger of the watch crystal no longer being excited with its natural frequency.

SUMMARY OF THE INVENTION It is the object of the invention to create an acoustical sound producer of the type mentioned at the outset in such a manner that the watch crystal is more likely to be excited with its natural frequency than with the known designs. For this purpose, it is now proposed that the sound producer be designed in such a manner that the pin is at least partially of ferromagnetic or magnetic material and extends into the alternating magnetic field of the electromagnetic system for direct excitation. Thus, in the design according to the invention only the electromagnetic system as a whole must be adjusted relative to the pin of the watch crystal. Moreover, this pin can be excited so as to produce sinusoidal oscillations, as the excitation is not produced by striking. Thus, in a sound producer according to the invention it is much simpler to excite the watch crystal with its natural frequency.

In the above described known sound producer, there is an air gap both between the tongue and one of the poles of the permanent magnets and one of the poles of the electro magnet. According to the invention, it is possible to achieve even better efficiency with the new signal producer in that pole shoes are attached on the poles of the permanent magnets facing the pin. with the free end of the pin being located between said pole shoes and in front of one pole of the electro magnet.

DRAWING Further characteristics and details of the invention can be seen from the following description and the enclosed drawings of a preferred embodiment of a sound producer according to the invention, in which FIG. 1 shows a vertical cross section through the watch crystal and the other members of the sound producer, with the exception of the excited oscillator circuit;

FIG. 2 shows a cross section along line 22 in FIG. 1; and

FIG. 3 shows a cross section along line 3-3 in FIG. 1.

DESCRIPTION The drawing shows a watch crystal 10 of plastic. Attached in a projection 12 formed on the watch crystal is an iron pin 14 which, as can be seen from FIGS. 1 and 3, has the shape of a strip of sheet metal and is of ferromagnetic or magnetic material.

Attached on a plate 16 of the watch, which is otherwise not illustrated, by means of a mounting angle 18 is an electromagnetic system, consisting primarily of an electro magnet 20 and two permanent magnets 22. The electro magnet has a coil 20a, surrounding a core 20b, whose free end forms one of the poles of the electro magnet. All magnets are attached to mounting angle 18, with pole shoes 24 being attached to the poles of permanent magnets 22 which face away from the latter and whereby pin 14 extends into the electromagnetic field between said pole shoes 24.

A conventional self-starting oscillator (not shown) which is switched on by the watch at the selected time, excites electro magnet 20 with the aid of mounting angle 18, the electromagnetic system 20, 22 is adjusted relative to pin 14 in such a manner that pin 14 does not adhere to core 20b, whereby watch crystal 10 is excited with its resonance frequency, to which of course the unillustrated oscillator circuit must also be matched.

A significant advantage of the sound producer according to the invention is also to be viewed into the fact that with it good feedback of the natural frequency of watch crystal 10 to the exciting oscillator circuit can be achieved.

It is also practical to excite with a multiple of the resonance frequency of watch crystal 10, whereby a ratio of 2 1 (3000 1500) is especially recommended.

Experiments by the applicant have shown that the current consumption of the sound producer according to the invention can be reduced to 2.5 3 mA while still generating a signal tone of sufficient intensity.

I claim:

1. An acoustical sound producer for clocks, especially for Wristwatches, comprising a watch crystal, an electromagnet system adapted to be excited by an oscillator, and a pin attached to the watch crystal, said pin being at least partially of ferromagnetic or magnetic material and extending into the alternating magnetic system for direct excitation.

2. The sound producer set forth in claim 1, wherein said electromagnetic system has an electro magnet arranged between two permanent magnets, pole shoes attached on the poles of the permanent magnets facing said pin with the free end of the pin being located be tween said pole shoes and in front of one pole of the electro magnet.

3. The sound producer set forth in claim I, wherein the entire electromagnetic system is adjustable as a unit relative to said pin. 

1. An acoustical sound producer for clocks, especially for wristwatches, comprising a watch crystal, an electromagnet system adapted to be excited by an oscillator, and a pin attached to the watch crystal, said pin being at least partially of ferromagnetic or magnetic material and extending into the alternating magnetic system for direct excitation.
 1. An acoustical sound producer for clocks, especially for wristwatches, comprising a watch crystal, an electromagnet system adapted to be excited by an oscillator, and a pin attached to the watch crystal, said pin being at least partially of ferromagnetic or magnetic material and extending into the alternating magnetic system for direct excitation.
 2. The sound producer set forth in claim 1, wherein said electromagnetic system has an electro magnet arranged between two permanent magnets, pole shoes attached on the poles of the permanent magnets facing said pin with the free end of the pin being located between said pole shoes and in front of one pole of the electro magnet. 